1. Field of the Invention
The present invention relates generally to rotary printing machines, and more particularly to a device for changing between single-side printing and perfecting printing in sheet-fed rotary printing machines.
2. Description of the Prior Art
The invention relates to a device whereby turning drums and press cylinders disposed between the individual printing units of a series-construction sheet-fed rotary printing machine can be changed over as required between a single-side printing configuration or a perfecting configuration.
In change-over type single-side printing or perfecting printing machines, the sheets are engaged by the printing cylinder via suckers or grippers disposed on the turning drum. These suckers or grippers suck or grip the front edge or rear edge of the sheets. In order to change the machine over from single-side printing to perfecting, and in order to adjust to different formats, it is necessary to make a phase shift between the printing cylinders and the turning drums.
DE Utility Model 8 319 431 discloses a device for changing over to single-side printing or perfecting as required. This device is characterized in that a clampable double wheel in a toothed wheel/toothed rim configuration is disposed on the turning drum and the required switching and clamping operations are carried out by hydraulic or mechanically actuated devices.
DE-OS 3 136 349 discloses a method of adjusting the drive, based on DD-WP 135 812. A double gearwheel is disposed on the printing cylinder trunnion. The first gearwheel is permanently connected to the trunnion, whereas the second gearwheel, which is a toothed rim, is clamped or released by spring force and a friction lining disposed on the flat side surface of a ring. The ring is toothed in addition to the first gearwheel. Adjusting members for hydraulically clamping or releasing the connection are disposed on the ring which transmits the contact pressure.
The required changeover to single side printing or perfecting, as represented by these devices is relatively expensive to achieve, which is a disadvantage. The hydraulic clamping devices are expensive and have to be located separately from the gear systems.
DE-AS 1,056,573 also discloses a drive arrangement with a central wheel. For each printing cylinder, there is a gear coupled to the central wheel. By means of intermediate planetary gear wheels there is brought about a translation into a slower rate. However, this solution cannot be arranged in a closed gear train and does not permit separate drive of individual turning drums. It is unsuited, therefore, for the changing over to single-side printing or perfecting printing.
In the roll machine building art there is also known an arrangement for length-register regulation. Thus, as shown in DE-AS 1,411,775, the drive of a form cylinder occurs from the main drive shaft over two gear wheels, a differential gear and its off-drive shaft. A servomotor controls the differential gear in such manner that the form cylinder is accelerated or retarded for the length-register adjustment. However, this solution cannot be arranged in a closed gear train in order to bring about a changing over to single-side printing or perfecting printing.